The present invention relates to a method and apparatus for concentrating and recovering platinum family metals from ceramic materials and, more particularly, to a pyrometallurgy process which may be used to remove volatile oxides of the platinum group of metals from a mixture of ceramic substrates.
Metals from the platinum family are normally refined from ore found most abundantly in Canada, South Africa, and Russia. Such ore usually comprises a mixture of the platinum family metals, along with nickel and traces of gold and silver. The ore is crushed, ground and treated by a flotation process which removes the sulfides along with the platinum group of metals. The sulfides and platinum group of metals are then roasted and blown against a matt. The material against the matt consists mostly of oxides of the platinum group. The platinum group metals are then separated by an electrolytic process and are further separated by continuing chemical processes. The processes outlined above are described in several references (see Treatise on Analytical Chemistry, edited by I. M. Kolthoff, Part II, Vol. 8, "Analytical Chemistry of Platinum Metals," published by Interscience, Division of John Wiley, 1963) and will not be described further here.
Another method for purification of iridium which is already 90 percent pure is disclosed in U.S. Pat. No. 3,867,137 by H. Inouye. This method does not disclose a means of recovering iridium from ceramic material since the fused silica tube used therein will react with many ceramic materials from which it is desirable to remove iridium or other platinum group metals.
In the history of precious metals, the current price of gold is of major concern. While gold has recently sold as high as $200 per troy ounce, iridium sold at $400 per troy ounce. Iridium and some of the other precious metals are not acclaimed commercially as are gold and platinum. However, these metals are valued for their special scientific capabilites and properties. For example, iridium is used to manufacture crucibles for high temperature crystal growth and as a catalyst in the chemical industries for refining various products. As these products are manufactured or refined, the iridium is often dissipated. It is the need to efficiently recover the dissipated iridium from ceramic material that has brought about the present invention.